If OA and OB be the tangents to the circle {x | vedclass

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Question

(b) Here the equation of $AB$ (chord of contact) is

$0 + 0 - 3(x + 0) - 4(y + 0) + 21 = 0$

$ \Rightarrow 3x + 4y - 21 = 0$&hellip;.$(i)$

$CM$

Vedclass · Accepted Answer

$\frac{4}{5}\sqrt {21} $

Vedclass · Answer

(b) Here the equation of $AB$ (chord of contact) is

$0 + 0 - 3(x + 0) - 4(y + 0) + 21 = 0$

$ \Rightarrow 3x + 4y - 21 = 0$&hellip;.$(i)$

$CM$ = perpendicular distance from $(3, 4)$ to line $(i)$ is

$\frac{{3 	imes 3 + 4 	imes 4 - 21}}{{\sqrt {9 + 16} }} = \frac{4}{5}$

$AM = \sqrt {A{C^2} - C{M^2}} = \sqrt {4 - \frac{{16}}{{25}}} = \frac{2}{5}\sqrt {21} $

$	herefore \;\;AB = 2AM $

$= \frac{4}{5}\sqrt {21} $ .

If $OA$ and $OB$ be the tangents to the circle ${x^2} + {y^2} - 6x - 8y + 21 = 0$ drawn from the origin $O$, then $AB =$

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